docs: def header(self):
          '''
          Format this element's metadata as it would appear in a PLY
          header.
  
          '''
          lines = ['element %s %d' % (self.name, self.count)]
  
          # Some information is lost here, since all comments are placed
          # between the 'element' line and the first property definition.
          for c in self.comments:
              lines.append('comment ' + c)
  
          lines.extend(list(map(str, self.properties)))
  
          return '\n'.join(lines)